1. Field of the Invention
The present invention relates to a method of providing a record carrier having a recording layer with areas having modified optical properties, wherein the method involve heating a recording layer locally by radiation pulses of a write power adequate to bring about the change in optical properties.
The invention further relates to a apparatus for providing a record carrier having a recording layer with areas having modified optical properties. The apparatus comprises means for scanning the layer by means of a write beam, means for modulating the power of the radiation beam to obtain radiation pulses having a write power which is adequate to bring about the change in optical properties, means for adjusting the write power, and detecting means arranged to detect the proportion in which a property, indicative of the changed optical property, changes in the radiation originating from the part of the record carrier being scanned.
2. The Related Art
One such method and apparatus are known inter alia from U.S. Pat. No. 4,225,873 which describes an optical information recording device for recording information in the form of a pattern of areas having modified optical properties in a radiation-sensitive layer of an optical record carrier. In order to verify the pattern thus formed, this pattern is read by means of an additional verification beam while the areas are being formed. On the basis of the pattern being read, the write power is adapted continually according to predetermined criterion in order to make the recorded areas largely independent of changing recording conditions, such as for example contaminations of the record-carrier surface or a change in the shape of the scanning spot formed on the radiation-sensitive layer by the write beam. Scanning the radiation-sensitive layer with the additional verification beam poses a problem because it is technically difficult to realize and it involves substantial cost. This applies in particular to recording apparatus intended for the consumer market because in that case the cost aspect has additional emphasis.